It's no surprise that online ad spending has dramatically increased compared to print advertising (think yellow pages and newspapers), but where precisely should you buy ads? How do you know which site is best for your ad dollars? Fortunately, eMarketer's latest insight helps answer these essential questions.

Presently, there are five firms who make up two-thirds of online ad spending in the U.S. Can you guess which ones? Let's take a look at the facts. Here's the current ranking:

1) Google

2) Yahoo

3) Facebook

4) Microsoft

5) AOL

What makes Google the number one destination for online ads? According to eMarketer, "Google’s gains are being driven largely by search." Not to mention, Google has benefitted from the so called "network effect," which means it has attracted many consumers overtime, which in turn has resulted in more advertisers. It becomes a never-ending cycle in which both consumer and advertiser stay committed to Google. Google's constant innovation (think about the Google+ project) keeps users on its site--people have a tendency to be fascinated by something new--it keeps them engaged.

These noteworthy findings from eMarketer present a clear message to businesses. If you are not already buying ads online, a great place to start would be Google. If your budget permits then it may also be a good idea to invest in the other top two companies—namely Yahoo and Facebook. Facebook, as you hopefully know, is the most popular social networking site in the U.S with over 750,000,000 members.

Did you already know that Google was the number one online ad destination? Are you currently advertising on any of these sites? If so, have you seen your return on investment yet? Finding it complicated to setup it up right without draining your wallet?

About Alan Moore: Alan is an Internet Marketing Consultant with ReachLocal Baltimore. His mission is to help you increase your revenues and decrease unproductive advertising expenses through proven, online marketing strategies. He manages over $1,000,000 in yearly marketing budgets and has worked with local businesses, agencies and the US government. Give him a call at (877)655-3438 to schedule a free consultation.